Dual brush function in texture painting?
Edit: No, there isn't a way to switch between two textures based on pressure in the brush itself. The example given shows how to switch between two colors with the same mask texture used, which is closer to what the linked video showed at the time mark given. IF you simply want to mix two textures, one can be set to the brush texture and one to the brush texture mask, and use separate mapping.

If the gradient is what you are looking for, here is a quick example of the settings to use with a 'Texture Mask' brush and using a two stop gradient set to pressure.

Here I set an image of a square to the main brush texture calculate alpha, rake and use stucco on brush mask set to 'cutoff' for pressure. I hope this one maybe helps. Square has to be mapped to like 1.60 instead of 1 so that there is visibility of the edges inside the brush sphere.